1. Field of the Invention
The present invention is directed towards walk-in cooler/freezer cold doors and more particularly towards insulated doors to be used in refrigerated, freezer, or warmer walk-in units wherein the temperature is different inside and outside the unit, and utilized by personnel walking or carrying items into and out of the unit using lifting and transporting equipment.
2. Description of the Related Art
Coolers are widely used. A myriad of applications calls for maintaining temperatures at a reduced level. Some examples include food processing plants, dairies, bakeries, bottling plants, restaurants, supermarkets, hospitals, and school cafeterias. In the medical setting, coolers are used to maintain the temperature of test samples and medications. In the restaurant business, coolers are used to keep food items, beverages etc. at a certain temperatures. The refrigerated compartment of such coolers may be kept below 32° F. Hence, coolers are often referred to as refrigerators or freezers. In commercial settings, coolers are often large enough for a person to walk into. The contents of the cooler are frequently accessed; hence the doors of the coolers are opened frequently. With large commercial units, the access often includes use of dollies and heavy duty equipment such as fork-lifts to hold pallets of items. Every time the cooler door is opened it can lead to collisions between the door and the person entering with equipment such as pallets jacks, forklifts, and the like, causing damage to the door.
Walk-in cooler or freezer door manufacturers generally use 4″ rigid foamed in-place non-CFC urethane foam insulation inside the doors, which is then enclosed with 26 gauge white stucco embossed galvanized steel shell. U.S. Pat. No. 2,726,424 describes an example of this type of door. The cooler, or freezer door provides access to the cooler or freezer box and workers utilize hand carts, pallet jacks and forklifts, for the purposes of loading and unloading goods and merchandise. Collisions with the door are common and result in dents bending, and structural damage on the door. Occasionally, a 3/16″ aluminum diamond plate is installed to the lower section of the door, to absorb these impacts in an attempt to prevent the door from cave-in. However, over time, the damage sustained to the door from these impacts still requires repair or replacement of the door. This shortened lifespan of the door becomes a costly expense for the customer.
A problem with the present cooler door construction on commercial coolers or freezers is that walk-in doors for these coolers and freezers on the market, though properly constructed, are often not fabricated to withstand adverse conditions such as, severe impacts from pallet jacks or fork lifts, condensation, infiltration or resulting corrosion. The impacts described above eventually break the outer skin of the shell, often made of steel, apart from the insulation, causing the door to lose its form and shape. Once the door is damaged and or deformed, it is no longer capable of keeping a tight fit that is desired and necessary to keep the cold air in and warm air out of the cooler. The effect of this being loss of large amounts of refrigeration energy and the collection of condensation on and inside the door and box. A subsequent problem with the damaged door is loss or damage of product stored in the cooler. Customers lose inventory due to product shrinkage because the cold box is no longer capable of keeping the temperature needed to properly store produce and other perishable goods or products. The presence of condensation on or around the door also leads to ice accumulation in the cold box, which causes further damage and also leaves the box susceptible to mold and contamination. Lastly, contact with exposed, protruding metal from the damaged and/or deformed door can cause serious injury to workers. Accordingly, there remains a need in the industry for a door to a cold box capable of withstanding the rigors of commercial use, having durability, and allowing for energy conservation, as well as maintaining a suitable lifespan.